Today's New York Times article by Hindman and Cukier "More News, Less Diversity" cites a study (with NEC) of linking for political sites.  Their argument is that existence of the Internet and its open linking is not support for the FCC ruling that invites concentration news ownership. Phenomena observed include: political topics are heavily dominated links to a few websites (which search engines will prefer), few websites more than 1 link to them (thus difficult to reach and not acknowledged by dominant sites), and winner-takes-all behavior will increase traffic flow to top sites. The phenomena is dubbed Googlearchy. This looks like a great experimental contribution to web research, analyzing over 3M pages on multiple topics.

Our experiment on the sunny personality of search engines has similar conclusions, that branding and popularity will drown out dissent and controversy unless the searcher deliberately seeks balanced results, work that the naive searcher is unlikely to perform.